Tyson Ross is headed back to the minors in a new role after making one start for Oakland in place of suspended Bartolo Colon.
Matt Joyce hit a two-run double in a five-run fifth inning against Ross, and Tampa Bay beat the Athletics 5-0 on Thursday night. Alex Cobb pitched a four-hitter for his first major league shutout as the surging Rays pulled within 2½ games of the first-place New York Yankees in the AL East.
After the game, Ross was told he was being sent back to Triple-A Sacramento to work out of the bullpen and that he will rejoin the team when rosters expand in September.
"Now I've just got to move forward," Ross said. "Learn as much as I can about relieving, and be ready come September. I'm excited about the opportunity. Out of the 'pen, I think I have a chance to help this team win some games."
Luke Scott also doubled for the Rays in the fifth against Ross (2-9), recalled from Sacramento when Colon received a 50-game suspension Wednesday for testing positive for testosterone. The Rays batted around in the big inning, which also included RBI singles by Sam Fuld and Evan Longoria.
Ryan Roberts broke the scoreless tie with a sacrifice fly.
"I felt good out there," Ross said. "Felt like I was throwing the ball well. Obviously, the one inning bit me. It's a situation I'm going to have to pitch out of."
Ross, making his first start for the A's since June 28, pitched six-plus innings. He gave up nine hits while striking out six.
"It was just limiting the damage, that's what I told him," Oakland manager Bob Melvin said. "For the most part, that's as good stuff as we've seen him have. Plus-fastball with good movement. As good a slider as we've seen, and found a change that's workable for him. He had three pitches going tonight, just couldn't limit the damage in the one inning that they ended up scoring on him."
Oakland dropped into a tie with Baltimore and Detroit for the AL's second wild-card spot, 2½ games behind the Rays. The teams finish their three-game series Saturday and get a rare Sunday off because the Republican National Convention begins Monday in Tampa.
The A's, who have been shut out 15 times this season, did not have a travel day after beating Minnesota at home on Wednesday afternoon.
"Now more so, it's more surprising than earlier in the year when we had a string of them," Melvin said. "We've started to figure out the personnel better here, which enables us for the most part to combat that. We do every now and then have a game like this currently where we get shut out. I don't see us a team that has been shut out that many times."
Stephen Drew had two hits for Oakland, including a fourth-inning single that snapped an 0-for-22 slide. It was his first hit for the A's since he was acquired from Arizona in a trade.
Cobb (8-8) struck out eight and walked two in his second career complete game, both this season. He bounced back from a poor outing against the Los Angeles Angels to win for the fourth time in five starts.
It was the 14th win in 17 games for the Rays and their seventh shutout since July 19. They have pitched 13 shutouts this season, second-most in the majors behind the Angels (15).
It's the closest the Rays have been to first place since they were 2½ out before games of June 16.
Cobb allowed 12 hits and eight earned runs in 2 2-3 innings at Los Angeles on Saturday night, the only time this month a Rays pitcher has given up more than four runs. The Rays came back from an 8-0 deficit to win that game and take Cobb off the hook.
"Nothing worked the last time. And to his credit, he just threw that in the trash can and did this tonight," Rays manager Joe Maddon said.
NOTES: Oakland will add a reliever to the roster for Friday night's game. ... Melvin said INF Brandon Inge (sprained right shoulder) is ready to start a minor league rehab assignment with Sacramento. ... Athletics RHP A.J. Griffin (right shoulder) allowed three runs and four hits over 2 1-3 innings in his first rehab start Wednesday night for Sacramento.